1. Field of the Invention
This invention relates to activation means for lights used in surgical, medical and dental procedures requiring maintenance of sterility.
2. State of the Art
The need for a dental or medical practitioner to maintain sterile hands during surgery and other therapeutic procedures is well known, as is the need for good lighting of the therapeutic field. It is known to provide surgical light fixtures with sterilizable handles and/or handle covers to permit a light to be focussed or adjusted by the practitioner to illuminate a desired area without contaminating the practitioner's hands. Such a sterilizable handle or handle cover must be replaced between each procedure or patient. Also, the handle or handle cover must be sterilized, or purchased in a sterile condition, adding to the cost of purchase/use of the device.
Several kinds of touchless switches or relays are known, and have been employed for various uses. For example, a passive infrared-responsive switch which detects infrared radiation from a person can be used to turn on a light as the person enters a room, as described in U.S. Pat. No. 4,873,469. So-called "active" infrared switches, which emit an infrared beam at a location and have a detector placed to detect infrared light reflected from that location, have been used to activate hand dryers, towel holders, and water faucets (see for example U.S. Pat. Nos. 4,876,435, 4,796,825, 4,767,922, 3,480,787, 3,670,167, and 3,576,277). In a medical or dental environment, touchless switches would allow a practitioner to operate a light without jeopardizing manual sterility, and without requiring replacement and/or sterilization of the switch between patients.
Accordingly, a need remains for an operatory light for dental or surgical use which has a touchless switch mechanism. Desirably, such a touchless switch will be able to accurately discriminate "true" signals from false in the ambient light environment of the operatory room.